Why does Performance Health Check Widget display "Unavailable" during the upload speed check when Tomcat is used for application server.

This has been identified as a product defect under https://jazz.net/jazz/web/projects/Jazz%20Foundation#action=com.ibm.team.workitem.viewWorkItem&id=368566
The problem is caused by a fix in Apache Tomcat that imposes a limit of 2MB on the amount of data Apache Tomcat will swallow for an aborted upload:
Fix CVE-2014-0230: Add a new limit, defaulting to 2MB, for the amount of data Tomcat will swallow for an aborted upload.

Workaround is to add the following line into the server.xml for the tomcat server.
 maxSwallowSize="-1"

The server.xml is located in the following folder:
CLM Install Directory\server\tomcat\conf\

Once located the file. Open it in a notepad find the "Connector port" entry which reflects the port which your server is listening on. By default you should see Connector port="9443".
Add the line mentioned above within the Connector tag. Then save and restart your server.
Example:
Connector port="9443"
               connectionTimeout="20000"
               maxHttpHeaderSize="8192"
               maxThreads="150"
               minSpareThreads="25"
               enableLookups="false"
               disableUploadTimeout="true"
               acceptCount="100"
               scheme="https"
               secure="true"
               clientAuth="false"
               keystoreFile="ibm-team-ssl.keystore"
               keystorePass="ibm-team"
               maxSwallowSize="-1"
           protocol="HTTP/1.1"
           SSLEnabled="true"
......